Rubber blends containing an hydrogenated styrene butadiene random copolymer

ABSTRACT

A RUBBER VULCANIZABLE COMPOSITION HAVING AN INCRESASED GREEN STRENGTH, WHICH COMPRISES A BLEND OF (A) AT LEAST ONE POLYMER SELECTED FROM THE GROUP CONSISTING OF NATURAL RUBBER, POLYISOPRENE, STYRENE-BUTADIENE COPOLYMER, POLYBUTADIENE, BUTYL RUBBER AND ETHYLENE-PROPYLENE TERPOLYMER AND (B) FROM 5 TO 95 PARTS BY WEIGHT OF SAID BLEND, GENATED COPOLYMER PER 100 PARTS BY WEIGHT OF SAID BLEND, SAID HYDROGENATED COPOLYMER HAVING POLYMERIC MONOMER UNITS WHICH CONSIST OF (1) STYRENIC UNITS, (2) CONJUGATED DIOLEFINIC UNITS, AND (3) HYDROGENATED CONJUGATED DIOLEFINIC UNITS, WHEREIN THE STYRENIC UNITS ARE RANDOMLY DISTRIBUTED IN THE POLYMERIC MONOMER UNITS.

United States Patent 3,798,190 RUBBER BLENDS CONTAINING AN HYDRO- GENATED STYRENE BUTADIENE RANDOM COPOLYMER Toshio Yoshimoto, Takaaki Imamura, 'Kazuo Tanaka,

and Arata Miyagi, Tokyo, Japan, assignors to Bridgestone Tire Company Limited, Tokyo, Japan No Drawing. Continuation-in-part ofabandoned application Ser. No. 677,731, Oct. 24, 1967. This application Aug. 19, 1970, Ser. No. 64,959

Claims priority, application Japan, Nov. 3, 19 66,

ll/72,485 Int. Cl. C08c 9/04, 9/08 US. Cl. 260- 2 Claims ABSTRACT OF THE DISCLOSURE (1) styrenic units, (2) conjugated diolefinic units, and (3) hydrogenated conjugated diolefinic units,

wherein the styrenic units are randomly distributed in the polymeric monomer units.

This invention relates to a new rubbery, vulcanizable composition having increased green strength and other properties such as good heat resistance, high resilience and high tensile strength after vulcanization. The term green strength in this specification means the tensile strength of a rubbery polymer or a rubbery composition in the unvulcanized state.

This application is a continuation-in-part of the copending application Ser. No. 677,731 filed on Oct. 24, 1967, and now abandoned.

The first object of this invention is to provide a. method for improving theaging properties, resilience and green strength of natural rubber, polyisoprene and styrenebutadiene copolymers and to provide a new rubber vulcanizable composition suitable for high-speed tires and other articles.

The second object of this invention is to provide a method for improving the green strength and tensile strength after vulcanization ofpolybutadiene and to provide a new rubbery vulcanizable composition suitable for tires and other articles.

The third object of this invention is to provide a method for improving the green strength and high temperature aging properties after vulcanization of butyl rubber and ethylene-propylene terpolymers and to provide a new rubbery vulcanizable composition for rubber articles exposed to high temperature conditions.

Other and further objects of this invention will become her at the step of forming the green case of a tire. Low heat-build-up is attained by high resilience of used rubber.

I We found that the aging properties, resilience and green strength of natural rubber, polyisoprene and styrenebutadiene copolymers are remarkably improved by blending them with an hydrogenated copolymer consisting of styrenic units, conjugated diolenfinic units of hydrogenated conjugated diolefinic units, the styrenic units being randomly distributed in the hydrogenated copolymer. Further we found that the properties required for high-speed tires are not deteriorated by such blending but are improved in some respects. For example, tensile strength after vulcanization of styrene-butadiene copolymer is remarkably improved.

Therefore, the present invention provides a rubbery vulcanizable composition comprising a blend of (a) at least one polymer selected from the group consisting of natural rubber, polyisoprene and a styrene-butadiene copolymer and (b) from 5 to parts by weight of an hydrogenated copolymer per parts by weight of said blend, said hydrogenated copolymer having a secondary transition temperature over 100 C. and polymeric monomer units which consist of (1) styrenic units of from 5 to 60 percent by weight,

(2) conjugated diolefinic units of more than 2 percent by weight and (3) hydrogenated conjugated diolefinic units of more than 10 percent by weight,

wherein the styrenic units are randomly distributed in the polymeric monomer units.

The hydrogenated copolymer utilized in the present invention is prepared by selectively and non-destructively hydrogenating diolefinic units of the random copolymer formed from polymerizing styrene and a conjugated diolefin in the presence of the special soluble catalyst described infra.

The styrene content of the starting copolymer of styrene and a conjugated diolefin prior to hydrogenation may be widely varied. From 5 to 60 percent by weight of styrene content is preferably used, since a copolymer having more than 60 percent of styrene by weight provides a resinous hydrogenated copolymer and a copolymer having less than 5 percent of styrene by weight provides an hydrogenated copolymer with poor roll-processibility. From 10 to 30 percent by weight of styrene content is more preferably used.

The amount of the hydrogenated conjugated diolefinic units may be varied widely, but more than 10 percent by weight of the hydrogenated conjugated diolefinic units is preferable to exhibit their features and at least 2 percent by weight of the remaining conjugated diolefinic units is preferable to allow the copolymer to covulcanize with a rubber to be blended with the hydrogenated copolymer.

The content of the hydrogenated copolymer to be blended with natural rubber, polyisoprene and a styrenebutadiene copolymer may be varied widely. From 5 to 95 parts by weight of the hydrogenated copolymer are blended per 100 parts by weight of the blend depending upon the uses of the resulting rubbery compositions. The larger the amount of the hydrogenated copolymer, the higher the green strength, aging resistance and resilience of the rubbery composition of the present invention.

The second object of this invention will be understood by the following description. Compounds made from polybutadiene as the only rubber cannot be used in tires, in spite of its good abrasion-resistance and high resilience, since it has poor green strength, poor roll-processibility and poor tensile strength after vulcanization.

We found that three disadvantages of polybutadiene are remarkably improved by blending it with an hydrogenated copolymer consisting of styrenic units, conjugated diolefinic units, the styrenic units being randomly distributed in the hydrogenated copolymer. Further, we found that the properties required for tires are not deteriorated by such blending but are improved in some respects. For example, by such blending the poor heat resistance of polybutadiene is improved.

The present invention provides a rubbery vulcanizable composition comprising a blend of (a) polybutadiene and (b) from 20 to 95 parts by weight of a hydrogenated copolymer per 100 parts by weight of said blend, said hydrogenated copolymer having a secondary transition temperature over 100 C. and polymeric monomer units which consist of (1) styrenic units of from to 60 percent by weight,

(2) conjugated diolefinic units being larger by weight than hydrogenated conjugated diolefinic units and (3) hydrogenated conjugated diolefinic units of more than percent by weight,

wherein the styrenic units are randomly distributed in the polymeric monomer units.

The hydrogenated copolymer utilized in the present invention is prepared by selectively and non-destructively hydrogenating diolefinic units of the random copolymer formed from styrene and conjugated diolefin in the presence of the special soluble catalyst described later. The content of styrene in the copolymer may be varied widely. A copolymer having from 5 to 60 percent by weight of styrene content is preferably used as the starting material, since a copolymer having more than 60 percent of styrene by weight provides a resinous hydrogenated copolymer and a copolymer having less than 5 percent of styrene by weight gives hydrogenated copolymer with poor roll-processibility. The tensile strength of hydrogenated-polybutadiene having no styrene content is lower than that of polybutadiene, and the tensile strength of the blend is too low to be used for tires. From 10 to 30 percent by weight of styrene content is more preferably used.

The greater the amount of the hydrogenated copolymer blended with a polybutadiene, the higher the tensile strength of the blend. However, a blend of less than parts by weight of the hydrogenated copolymer does not have sufficient tensile strength after vulcanization for tire application. Therefore, from 20 to 95 parts by weight of the hydrogenated copolymer is preferably used. In order to exhibit a remarkably strong tensile strength, it is more preferable to use greater than 50 parts by weight of the hydrogenated copolymer.

Further, it is important to select the proper range of content of the hydrogenated conjugated diolefinic units in the hydrogenated copolymer to obtain good building-tack and the desired tensile strength of the blend of the present invention for tire application. When the hydrogenated conjugated diolefinic unit content is greater than 50 percent by weight, a rubbery composition of the present invention will be too hard at room temperature resulting in low building-tack insufficient to form a green case of a tire. When the hydrogenated conjugated diolefinic unit content is less than 10 percent by weight, the green strength and tensile strength of a blend of the present invention will not be improved.

The third object of this invention will be understood by the folloying description. Ethylene-propylene terpolymer and butyl rubber have superior heat-aging resistance, but they have some demerits at high temperatures over 120 C. Namely, when aging at high temperature over 120 C., the ethylene-propylene terpolymer becomes hard and brittle, and the butyl rubber create soft and sticky. These demerits become large obstacles for high temperature uses. On the other hand, green strength is very important for producing uniform rubber articles.

We found that unbalanced h at-deterioration and the green strength of ethylene-propylene terpolymer and butyl rubber are remarkably improved by blending them with a hydrogenated copolymer consisting of styrenic units, conjugated diolefinic units and hydrogenated conjugated diolefinic units, the styrenic units being randomly distributed in the hydrogenated copolymer. Further, we found that the properties necessary for rubber articles exposed to high temperature conditions are not deteriorated by such blending but rather improved in some respects. For example, the tensile strength or tear resistance of ethylene-propylene terpolymer or butyl rubber is remarkably improved, because of good covulcanization between components of the blend.

The present invention provides a rubbery vulcanizable composition comprising a blend of (a) at least one polymer selected from the group consisting of ethylene-propyL ene terpolymer and butyl rubber and (b) from 5 to parts by weight of an hydrogenated copolymer per parts by weight of said blend, said hydrogenated copolymer having a secondary transition temperature over 100 C. and polymeric monomer units which consist of (1) styrenic units of from 5 to 60 percent by weight,

(2) conjugated diolefinic units of more than 2 percent by weight, and

(3) hydrogenated conjugated diolefinic units being larger by weight than conjugated diolefinic units,

may be widely varied. From 5 to 60 percent by weight of styrene content is preferably used, since the copolymer with more than 60 percent of styrene provides resinous an hydrogenated copolymer and a copolymer with less than 5 percent of styrene yields an hydrogenated copolymer with poor roll-processibility. From 10 to 30 percent by weight of styrene content is more preferably used.

The amounts of the hydrogenated conjugated diolefinic units of the hydrogenated copolymer utilized in the present invention must be larger than the amounts of conjugated diolefinic units in order to attain the object of the present invention. For example, when the amounts of the hydrogenated units are less than the amounts of the unhydrogenated diolefinic units, the blend of the present invention does not possess tensile strength adequate for use in rubber articles exposed in high temperature circumstances due to more than two times greater than the amounts of unhydrogenated diolefinic units. However, more than 2 percent by weight of unhydrogenated diolefinic units is necessary in order to use an economical vulcanization method using sulfur as a vulcanizing agent.

The content of the hydrogenated copolymer blended with ethylene-propylene terpolymer and butyl rubber may be varied widely. From 5 to 95 parts by weight of the hydrogenated copolymer are blended per 100 parts by weight of the blend depending upon the use of the resulting rubbery compositions. The larger the amount of hydrogenated copolymer are, the higher the green strength and heat-deterioration resistance of the rubbery composition of the present invention.

Chlorinated butyl rubbers are usable in the same manner as butyl rubbers in the blend with the hydrogenated copolymer of the present invention.

tion, solution polymerization or emulsion polymerization by the use of radical type initiator, ionic type initiator or Ziegler type initiator. The solution polymerized copolymers are preferably used, because the hydrogenation of these copolymers proceeds under milder conditions, for example, lower temperature, lower hydrogen pressure and shorter reaction time, than that of copolymers prepared by other types of polymerization. A number of catalysts are used in solution polymerization of styrene with conjugated diolefin. Examples of these catalysts include the catalyst based on lithium metal or organolithium compounds, the catalyst obtained by combining of transition metal compounds and organometallic compounds of Group 1, 2 or 3 metals, and the Alfin catalyst. It is preferable to combine styrenic units with diolefinic units not in block but randomly. A desirable rubbery composition suitable for producing rubber articles can be obtained by using the hydrogenated random copolymer.

The hydrogenation of the random copolymer is carried out in a viscous solution by the'use of an hydrogenation catalyst. The catalysts which can carry out the selective hydrogenation of diolefim'c units may be preferably used. When the styrenic units and the diolefinic units of the copolymer are non-selectively hydrogenated the obtained polymer often becomes resin like and is not suitable for manufacturing rubber articles. An ordinary reducing metal catalyst such as Raney nickel and nickel kieselghur makes it necessary to use a large amount of catalyst, a high reaction temperature of from 150 to 200 C. or higher and a high hydrogen pressure in order to hydrogenate the copolymers efiiciently, because a solution of the copolymer is highly viscous as compared with that of low molecular weight olefins. These high temperature hydrogenation conditions often cause the degradation of the copolymers and the high molecular weight hydrogenated copolymers are not obtained. Further, these catalysts are easily poisoned by impurities which are removed only with difficulty and further the removal of such catalyst residue from the hydrogenated copolymers after hydrogenation is very difiicult. The catalyst residue left in the hydrogenated copolymers tend to deteriorate various properties of the composition or the cured composition containing them. Therefore, the use of an ordinary reducing metal catalyst for preparing the hydrogenated copolymer employed in the present invention is disadvantageous.

One of the suitable catalysts for preparing the hydrogenated copolymer employed in the present invention is the catalyst obtained by mixing an organic compound of a metal selected from the group consisting of nickel, cobalt and iron with an organometallic compound of the metal selected from the group consisting of Group 1, 2

and 3. This catalyst is soluble in the solution copolymer to be hydrogenated, and can carry out the selective hydrogenation of conjugated diolefinic units of the copolymer in a viscous solution form under a mild condition, for example, at near room temperature and under atmospheric pressure of hydrogen. A copolymer of high Mooney viscosity of even greater than 40 can be easily hydrogenated under such mild conditions that side reaction of thermal degradation or gelation does not occur. The obtained polymer has no undesirable properties resulting from the decrease of molecular weight or gel. Therefore, the hydrogenated copolymer prepared by the soluble catalyst has improved properties and does not lose various good properties of the starting polymer. Such an hydrogenated copolymer is suitable for attaining the object of the present invention.

Among the organic compounds of nickel, cobalt or iron, one of the preferable compounds is a metal carboxylate. The metal carboxylates include nickel naphthenate,

cobalt naphthenate, iron naphthenate, nickel octanoate,

6 quinoline and the like may be used. compounds include bis (acetylacetone) nickel, tris(acetylacetone)cobalt,

bis(ethyl acetoacetate)nickel, bis(salicylaldehyde)nickel,

bis S-hydroxyquinoline) nickel, tris(8-hydroxyquinoline)cobalt, bis(3,5-diisopropylsalicylic acid)nickel and the like.

Among the organometallic compounds of the metal of Group 1, 2 or 3, a metal hydrocarbyl compound of lithium, magnesium or aluminium is preferably used. Examples of such metal hydrocarbyl compounds include n-butyllithium, diethylmagnesium, triethylaluminium, triisobutylaluminium, triamylaluminium, diethylisobutylaluminium and the like. In addition to the organometallic compound, the metal hydrides such as lithiumaluminiumhydride and sodiumborohydride may be used.

Further, in addition to the above mentioned two component catalyst, a three component soluble catalyst consisting of the above mentioned two catalytic components and an olefinically or acetylenically unsaturated hydrocarbon is also preferably used. The soluble catalyst con sisting of the above mentioned two or three catalytic components is easily removed from the hydrogenated copolymer by adding a polar solvent such as acetone and alcohol to the reaction mixture containing the hydrogenated copolymer to precipitate the polymer. To make the removal of ,the catalyst residue more eifective, it is pref- The metal chelate erable to contact the reaction mixture with a polar solvent or water containing a small amount of acid. The catalysts used for preparing the hydrogenated copolymer used in the present invention are not limited to the above mentioned soluble catalyst. Other catalysts which can direct the selective hydrogenation of diolefinic units of high molecular weight copolymers without degradation or gelation' may be used.

Any usual method may be used in blending a polymer selected from the group consisting of natural rubber, polyisoprene, styrene-butadiene copolymer, polybutadiene, butyl rubber and ethylene-propylene terpolymer with the hydrogenated copolymer. A convenient method for preparing such a composition is to blend the materials on a mill roll, in a Banbury mixer or a kneader. The temperature employed in the blending operation may be varied widely depending upon the characteristics of the materials. If desired, rubber chemicals such as a carbon black, a processing oil, an accelerator and sulphur may be compounded with the rubbers. Another convenient method is to mix the solution of rubbery polymers of olefins with the solution of hydrogenated copolymers, after which the resulting solution is treated by conventional methods, such as steam stripping or coagulation in a non-solvent to recover the rubbery composition.

The invention is illustrated in greater detail in the following examples which are not intended, however, to be unduly limitative of the invention.

EXAMPLE 1 An emulsion-polymerized styrene-butadiene random copolymer (styrene/butadiene: 23/77, ML-4 at C.: 52) was purified by a toluene/ acetone system, and 5 percent by weight solution of the copolymer in toluene was prepared. The solution was hydrogenated in the presence of a catalyst prepared by mixing nickel naphthenate and trimethylaluminium, the concentration of which were 8 mmol and 24 mmol per liter of the polymer solution respectively, at 25 C. under 10 kg. /cm. of hydrogen for 8 hours. After the catalyst was removed by adding methanol containing a small amount of hydrochloric acid to the reaction mixtures, the recovered hydrogenated copolymer was dried under a reduced pressure. The hydrogenatedrandom copolymer consisted of styrenic units of 23 percent by weight, but dienic units of 11 percent by weight and hydrogenated butadiene units of 66 percent by weight, which was determined by Kemp-Wijs method (A. R. Kemp and H. Peters: Ind. Eng. Chem., Anal. Ed., 15, 453, (1943)) and the infrared spectrum.

Secondary transition temperature of the hydrogenated copolymer was -37 C., which was measured by difierential scanning calorimeter. The hydrogenated copolymer was blended with natural rubber (RSS #3), styrene-butadiene copolymer rubber (#1502 styrene/butadiene= 23/77 by weight, ML-4 at 100 C.: 52) or synthetic polyisoprene rubber (Califlex IR-305) on a mill roll and then the compounding ingredients shown in the following Table 1 were continuously added thereto. The obtained rubbery compositions were molded and the green strength was measured by the tension test according to JIS-K- 6301. Then, they were cured at 145 C. for 30' to 60 minutes until the arrival of the best cure time defined as the time when the modulus oft rubbery composition reached 90' percent of maximum modulus.

The physical properties of the cured rubber compositions were measured by the method according to JIS-K- 6301 and the results are shown in the following Table 1.

These results show that green strength, resilient and heat-aging resistance of the styrene-butadiene copolymer are remarkably improved by blending the hydrogenated copolymer having varying hydrogenated butadiene unit contents.

EXAMPLE 3 r (a) p Styrenic units (percent by Weight) 18 23 50 Butadienic units (percent by weight) 48 33 Hydrogenated butadiene units (percent by 34 44 v 25 Secondary transition temperature C.) 71 -57 28 Fifty parts by weight of each hydrogenated copolymer were blended with 50 parts by weight of styrene-butadiene copolymer on a mill roll.

TABLE 1 Natural rubber Polyisoprene Styrene-butadiene copolyme 50 Hydrogenated copolymer. I 50 80 50 20 50 80 Carbon black ISAF 45 45 45 45 45 45 45 Aromatic oil 5 5 5 5 5 5 5 5 Zine 0xide 5 5 5 5 5 5 5 5 Stearic acid- 3 3 3 3 3 3 3 3 N-oxydiethylene-Z-benzothiazolesulten a 1 1 1 1 1 1 1 1 N-phenyLB-naphthylamine 1 1 1 1 1 1 1 1 1 Green strength (kg./C111. 4.5 10.4 38.1 81.0 2.8 19.6 2.0 5.6 27.5 72.0 Resilience (percent) 55.8 56.6 57.6 59.0 56.0 57.8 52.1 45.4 56.9 58.8 Tensile strength after aging at 120 C.for 24 hours (kg/emfl) 12 146 172 221 90 168 178 190 221 246 1 Abbreviation of Intermediate Super Abrasion Furnace. i

2 Measured by Dunlop method. 1,

These results show that the green strength, resilience Rubbery compositions and cured rubbers wereprepared and heat-aging resistance of natural rubber, polyisoprene and the physical properties were measured in the same and styrene-butadiene copolymer are improved by blendmanner. as shown in Example 1. The results are shown ing with the hydrogenated copolymer, and the blending 45 in, the following Table 3. ratio of the hydrogenated copolymer can be varied Widely.

EXAMPLE 2 TABLE 3 The hydrogenated emulsion-polymerized'styrene-butag ggfgf diene random copolymers having various contents of hy- V v copolymer (3) (b) (c) drogenated butad1?ne unlts were prepared m trength (k'gJ m Z) 20 155 5 4 3 manner as shown in Example 1. These hydrogenated co- %esil ilence (percent) 52.1 56.0 56.6 55.5 polYmers S (c) and (D) conslsted of the 178 182 205 190 lowing units: a r 1 (A) (B5 (c) (1 i I 1 These results show that the green strength, reslllence 8 617585 10un tspegc t y g eh l 2g and-'heat-aging resistance of styrene-butadiene copolymer 11 at 18111011111 S ercen We] i 7 Hydrogenated buliahiene Ymitsgmment by are improved by blendingthe hydrogenated copolymer Weight) 17 -44 59 66 having-a wide range of styrenecontent. Secondary transition temperature C.) 64 57 48 37 60 I .L v

'. EXAMPLE4 Fifty parts by weight of each hydrogenated copolymer I were blended with 50 parts by weight of a styrene-buta- Hydrogenated emulsion-polymerized styrene-butadiene diene copolymer (#1502) on a mill roll. Rubbery corn random copolymers having 23 percent by weight of positions and cured rubbers were preparedand'the physty enie units, 45 percent by weight of butadienic units ical properties were measured 1n the same manner as and 32 percent by weight of hydrogenated butadienic' shown in Example 1. The results are shown m the 101- it were prepared in the same manner as shown in lowing Table 2. Example 1. Secondary transition temperature of this co- TABLE 2 v polymer was 63 C. The resulting hydrogenated copolyst 8% mer was blended with polybutadiene rubber on amill rollbutgdiene and then the compounding ingredients shown in the fol- (A) (C) (D) lowing Table 4 were continuously added thereto. The

Green Strength (kg/ems) 2.0 3.5 5.4 15.2 27.5 rubbery compositions were molded and the green strength Resilience (Percent) was measured by the same method as shown in Exam- Tensile strength after aging at I 0., for 24hours (kg./cm.) 178 197 205 215 221 7 ple 1. Then, they were cured in the same manner as shown in Example 1 and tensile strength was measured by the 9 tension test according to JIS-K-6301. The results are shown in the following Table 4.

I EXAMPLE 6 The styrene-butadiene random copolymers having van- V. d a v d v TABLE4 ous styrene contents were hydrogenated until about half 1 2 3 4 of the butadienic units of the starting polymers were hy- 5 drogenated in the same manner as shown in Example 1. 'lggigrggtgtgggggggg }3? t3 g3 g3 Tdd dbtddddd hy d d pdymdd (a), (d), (d) and Carbon black ISAF 45 45 as 45 (d) consisted of the following units: gromatig oil 1;; 1(3) lg lg ir ii 1 7 1 7 1 7% 1 7? (a) (b) (c) (d) 11! mp g ggggggggqggggg 1018511 amid 1 1 1 j i illinlfifidiiiifiirl ii gar::::::::: 43 i3 53 32 Green strength (kg./em. 1.5 1.7 4.7 6.4 ggfl g butadlene (Percent by 40 38 25 Tensilestrength 161 169 242 admiral-itnratiartngtntnr 253:5333: -70 61 -28 These results show that green strength and tensile Flfty Parts by weight of each hyqrogenated copolymer 15 were blended with 50 art b Wei h f l b t d' e strength of polybutadiene are lmproved by blending the P S Y 8 t 0 P y u a 1611 hydrogenated copolymer, but more than parts by onamluronweight f hydrogenated copolymer are required to Rubbery compositions and cured rubbers were prepared prove tensile strength to a suflicient extent to be used and the Physlcal Propartles were measured In the ti li i 20 manner as shown 1n Example 4. The results are shown in a the following Table 6.

EXAMPLE 5 TABLE 5 The hydrogenated emulsion-polymerized styrene-butai diene random copolymers having various contents of diene (a) (b) (c) (d) hydrogenated butadiene units were p p in the Same Greenstrengtmkglcmd) L5 3L0 4 5 2'2 manner as shown in Example 1. These hydrogenated co- Tensile strength (kg-lam?) 161 128 195 209 190 ers (B) and (C) consisted of the fonowmg These results show that it is important to use an hydrogenated copolymer having a proper range of styrene (A) (B) (C) content, and the tensile strength of the blend with hy- St mic unit ementb Wei 23 23 23 drogenated polybutad ene having 0% styrene content is Bii tadienicunit s (perceribyeiglitiIIIIIZEI: 54 45 28 too low to be used 111 firess di fii ai t fgn siiififfiipfiiif? 63 .PiFY3522: 33 ii i EXAMPLE 7 a 35 The styrene-butadiene random copolymer (styrene/ Fifty parts by weight of each hydrogenated copolymer butadiene=25/ 75 y Weight, Mooney Viscosity at were blended with 50 parts by weight of polybutadiene C-=57) was prepared through solution polymerization on a mill roll and then the compounding ingredients as by the use of a catalyst based upon n-butyllithium. A 15 shown in Table 4 were continuously added thereto. volume percent solution of the obtained copolymer in Tackiness of the obtained compositions was measured by nxan was hydrogenated at 60 C. under 10 kg./cm. a i k. t t k t t oo t t re, Green pressure of hydrogen for minutes in the presence of a strength and tensile strength were measured by the same Catalyst Obtained y miXiIlg nickel naphtheflate and method as shown i E l 4 Th lt r Shown in ethylaluminium in the presence of dicyclopentadiene. The the following Table 5. concentration of nickel naphthenate was 1.5 mmol per 7 V I 5 g 45 liter of the copolymer solution to be hydrogenated and the molar ratio of nickel naphthenate/triethylaluminium/ 33a: dicyclopentadiene was Ai/l. After hydrogenation, the hy- (A) (B) (c) diene drogenated copolymer was recovered by adding acetone Gmnsmngth (kg/cm}, M M M2 L5 containing a small n f hydr chloric acid to the Tensile Strength (kg./cm. 207 210 224 161 copolymer solution and mixing a large amount of metha- 120 1101 with the copolymer solution to precipitate th hydrogenated copolymer. The thus obtained hydrogenated These results show that the higher green strengths and random copolymer consisted of 25 wt. percent of styrenic tensile strengths of polybutadiene are obtained by blendunits, 3.7 wt. percent of butadienic units and 71.3 wt. ing an hydrogenated copolymer with a greater content percent of hydrogenated butadiene units, which was deterof hydrogenated butadienic units. However, a blend of mined by the degree of unsaturation according to the hydrogenated copolymer having more than 50 percent Kemp-Wijs method and an infrared spectrum analysis. The by weight of hydrogenated butadiene units had a too low compounded stocks were prepared on a mill roll accordbuilding-tack to be used for a tire, and the blend of hying to the compounding recipe shown in the following drogenated copolymer having less than 10 percent by Table 7 and were cured to form a sheet. The physical weight of hydrogenated butadiene units did not exhibit properties were measured according to JIS-K-6301 and the properties required of the present invention. the results are shown in the following Table 7.

TABLE 7 Ethylene-propylene terpolymer (third component: ethylidene-norbornene,

Solution-polymerized styrene-butadiene random copolymer (styrene/butadiene=25l75 by weight, ML4=57) Chlorinated butyl rubber (ML-4=55) Butyl rubber (ML4=55) Carbon black (High Abrasion Furnace)" Aromatic oil Carbon black (General Purpose Furnace) Spindle oil Tackifier (alkylphenol) Zine oxide Stearic acid. Sulfur TABLE 7Continued Tetramethylthiurammonosulfidc 1.5 1.5 1.5 1.5 1.5 Tetramcthylthiuramdisulfide. 1 1 1 1 2-mercaptoimidazoline 1-5 Mercaptobenzthiazole 0.5 0.5 0.5 0.5 0.5 0 5 0.5 0.5 glrimethyldihygroquinoline polymer... 2.0 2.0 2.0 2.0 2.0 lg agnesium 0X1 e v Poly-p-dinitrobenzene 0 5 0 5 0.5 0.5

Cured at 145 C.

Tensile strength (kg/em!) 161 182 197 212 1 142 133 123 I 99 101 103 106 Elongation (percent) 400 375 375 360 170 470 310 400 500 460 460 510 Tear strength (JIs-B, kg./cm. 47 54 57 57 18 38 31 3e 39 35 31 34 These results show that the hydrogenated styrenebuta- 20 hours in 3 kg./cm. of air according to JIS-K-6301. The diene random copolymers can covulcanize with other results are shown in the following Table 9. polymers with low unsaturation and provide vulcanizates having desirable properties.

EXAMPLE 8 TABLE 9 The solution-polymerized styrene-butadiene random co- Cmpmmding mipe 1 2 3 l 4 polymer (styrene: 25.6 wt. percent, 1,4-cis-butadiene: Butyl rubber (ESSO-218) 100 70 so 70 18.8 wt. percent, 1,4-trans-butadiene: 31.1 wt. percent, f g g gggf fi g iz gggggig? 5 3351 515: 1,2-butadiene: 24.5 wt. percent) was hydrogenatedaccent) cording to the same method as shown in Example 7. 39 gggggg g gfifii gg f g igf fg fifiif 94.2% of the original butadiene were hydrogenated. Secent) 20 30 ondary transition temperature of this copolymer was gg figg figffijgffi s g- -55 C. The hydrogenated copolymer was compounded Spindle oil 32.5 with ethylene-propylene terpolymer and other ingredients fig ggl ggg p -a g 5 and then the obtained compounded stocks were cured at Tetramethylthiuramdisulfide 1 145 C. for 30 minutes. Sulfur 2 After the vulcanizates were aged at 160 C. or 180 C. Cured at 145 0. for 1.5 times of the best cure time for 24 hours in air, their hardness was measured accord- Before aged: ing to JIS-K-6301. The results are shown in the follow l l ardne s s (2 33 8g 3g onga on percen mg Table 1 re a e 2) a 122 a 1 81151 e S Tell em TABLE 8 Afiefiaggng: g 32 i 19' 40 '44 3.1 ness Compounding recipe 1 2 3 4 5 g og lef gfif a r l n g 2 3 529 0 115 g 0111. gf fgfigfi fff fffff fff?ff??? 25 75 Tengilestwngth -l m 18 21 "41 EPT Nordel100 100 75 2s 45 Y EPT Epsyn 40"; 100 25 e Carbon black (High Abrasion Furnace)- Aromatic oil V 5 g f anfylphefdfffmfdehyde 5 These results show that the softening of butyl rubber Steafic aeid I. 1 after aging at high pressure can be decreased by blendgflg fi ggf mmethyl dlhydmqmmlme: 50 ing it with the hydrogenated styrene-butadiene random cod polymer. e e Mercaptobenzothiazole v. .025 What IS d d 1S:

O 1. A rubbery vulcanrzable composition havlng a hlgh cured at 145 30 minutes green strength, improved aging properties and resilience Hardness com risin 66 71 rgbl d r tl t 1 1 tdf th After aged at 160 C.for24hours. 72 72 as 74 71 611 0 a eas one PQY Se Tom 1 6 After aging at 180 0. tor24h0urs---" 7a 74 72 75 72 group consisting of natural rubber, polylsoprene and 1 Sold by Du Pont. Third component is 1, 4-hexadiene, styrene'butadlene copolymgr a v v I, 2 gold by Japan Synthetic Rubber Co. Third component is ethylldene (b) from 5 0 parts by Welght 0f ahydrogenated'rannot omene' 6O domcopolymer per parts by weight of said blend, These results show that the mcrease of hardness of id hydrogenated copolymer'having a 'n y -p py e p ym after aging be p transition temperature over -100 c. and consistvented by blending them with hydrogenated styrene-butai f dlene random p y (1) styrene units of from S'to 60 percent by'weight, EXAMPLE 9 65 (2) butadien; units of more than 2 percent byt a weight an The same styrene-butadiene random copolymer as used (3 hydrogenated butadiene units of more m 10 m Example 8 was hydrogenated according to the same percent by Weight v method as shown in Example 7. Thus, hydrogenated 60- wherein the styr ene units are randomly distribpolymers having different degree of hydrogenation were 70 uted in the polymeric monomer units prepaqed then were compounded wlth butyl rubber.and 2. The composition as claimed in claim {wherein other ingredients. The compounded stocks were vulcanized St rene units of Said h dro enated co 01 m r r cm at C. for-1.5 times of the best cure time and the y t f y t 7 physical properties of the resulting vulcanizates were measm an amoun Tom 0 Percen y welg ured before and after they were ged at C. for 20 75 (References on following page) 13 14 References Cited FOREIGN PATENTS UNITED STATES PATENTS 879,134 1961 Great Britain 260-5 3 3 i l 2; JOHN c. BLEUTGE, Primary Examiner 1 a awa et 7. 2 3/1966 Hillard et a1 26O 8 5 R. B. TURER, Asslstant Exammer 3/1966 Korpman 260---5 US. Cl. X.R.

Holden et a1 260-876 260--23.7 M, 33.6 AQ, 41.5 R, 888, 889, 892, 894 

